Southern blot of pTK/RTK2 PCR (35 cycles) products, from transduced primary T cells in culture with or without GCV.

(A) PCR amplification of the HSV-Tk sequence in transduced/unselected T cells (TK0), transduced/G418-selected T cells (TK800) cultured in the absence of GCV and with 1 μg/mL GCV for 7 days (TK800 + GCV). (B) Transduced primary T cells after 8, 11, and 16 days of culture in the presence (1 μg/mL) or absence of GCV. Positive (DNA from G1Tk1SvNa vector producer cells) and negative controls (nontransduced primary T cells) were used.